"Are we talking hours, days or weeks? No idea really."
Apparently Icelandic volcanoes don't have as much gas as those in the Caribbean and other places, so it won't be years (of ash/dust thrown up).
The worry is that it will stop and start or that Katla may start up as well.
This is going to be messy...
Metcheck.com - Atlantic Jet Stream Forecast - [Updated on 15 April 2010 at 20:00] - Weather Feeds - Live Data - Long Range Weather Forecasts